morse(6): update documentation

- bump Dd
- use 'r' instead of 'D' from the original submission

usr.bin/morse/morse.6

@@ -29,7 +29,7 @@
 .\"	@(#)bcd.6	8.1 (Berkeley) 5/31/93
 .\" $FreeBSD$
 .\"
-.Dd June 7, 2005
+.Dd January 5, 2018
 .Dt MORSE 6
 .Os
 .Sh NAME
@@ -37,7 +37,7 @@
 .Nd reformat input as morse code
 .Sh SYNOPSIS
 .Nm
-.Op Fl elps
+.Op Fl elrps
 .Op Fl d Ar device
 .Op Fl w Ar speed
 .Op Fl c Ar speed
@@ -92,7 +92,7 @@ Echo each character before it is sent, used together with either
 .Fl p
 or
 .Fl d .
-.It Fl D
+.It Fl r
 Decode morse output consisting of dots and dashes (as generated by using
 the
 .Fl s